Re: Display Pg buffer cache (WIP)

Neil Conway wrote:
>
> I don't like accessing shared data structures without acquiring the
> appropriate locks; even if it doesn't break anything, it seems like just
> asking for trouble. In order to be able to inspect a buffer's tag in
> Tom's new locking scheme (not yet in HEAD, but will be in 8.1), you need
> only hold a per-buffer lock. That will mean acquiring and releasing a
> spinlock for each buffer, which isn't _too_ bad...
>
>

I am looking at this bit now.

I take the first part to mean that don't need to wrap
LWLockAcquire(BufMgrLock, LW_EXCLUSIVE) ... LWLockRelease(BufMgrLock)
around the inspection of the buffers (?)

This per buffer lock, are we talking about LockBuffer(buf,
BUFFER_LOCK_SHARE) ... releaseBuffer(buf) ?

If so, it looks like I need to do some stuff with ResourceOwners,
otherwise ReleaseBuffer will fail (or am I wandering up the wrong track
here?). I am using anoncvs from yesterday, so if Tom's new scheme is
*very* new I may be missing it.

Thanks

Mark